If you do it correctly – it works a treat. Poor installation technique is a primary cause of sealing failure. Following a structured application process ensures the adhesive flows correctly without damaging the polyolefin jacket or the underlying wires. Utilizing dual-wall adhesive-lined heat shrink tubing correctly is fundamental to constructing reliable, resilient heat shrink. By understanding the specifications, avoiding exaggerated waterproof claims, strictly adhering to diameter recovery sizing rules, and employing controlled heating techniques, installers can ensure long-lasting protection against mechanical stress and environmental degradation.
Size for Shrinkage
Measure the required length, keeping in mind that heat shrink tubing experiences longitudinal shrinkage. As the tube decreases in diameter, it also tends to contract slightly in length, typically by five to ten percent. Ensure the cut tubing overlaps the cable insulation by at least 15mm to 25mm on either side of the terminal or splice.
Position Centrally
Clean the cable insulation to remove oils, dirt, or residues that might inhibit adhesive bonding. Cut the tubing cleanly with sharp side cutters or scissors. A jagged edge can act as a stress concentrator, leading to splitting during the recovery phase. Slide the tubing over the wire, complete your crimp or connection, and then center the tubing over the joint.
Install with Care
Heat with a dedicated heat gun with a reflector nozzle rather than an open flame. An open flame lacks temperature control and can easily scorch the tubing, rendering it brittle and compromising the integrity of the product. Once the heat has been applied, then cooling the result is also integral to a successful installation.
- Start Centrally: Begin applying heat evenly around the center of the tubing. This allows the tubing to grip the middle of the connection first.
- Work Outward: Progressively sweep the heat gun toward one end, rotating the cable if possible to ensure uniform shrinkage. Once one side has fully recovered, return to the center and work toward the opposite end. This method forces trapped air out the ends, preventing air pockets that compromise the seal.
- Work the Glue: You will know the process is complete when the tubing is smooth and conforms tightly to the connection geometry. A small fillet or bead of melted adhesive should be visible seeping from the ends of the tubing, confirming a successful internal seal.
- Cool with Care: Allow the assembly to cool naturally in ambient air. Do not manipulate, bend, or pull the connection while the adhesive remains in a liquid state, as this will break the bond before it sets.